The invention relates to apparatus for the cleaning of closed compartments by means of sprayed-out liquid, and comprising a housing with a stationary part to which the liquid is supplied, and on which there is mounted a rotatable part having a hub with spray nozzles suspended in bearings therein. A turbine driven by the liquid and having a planet gear mounted in the stationary part is provide for turning the rotatable part and the nozzles in such a manner that the liquid sprayed out through the nozzles during rotation can sweep the whole of the interior of the compartment.
Apparatus of this kind is used especially for the internal cleaning of tanks within the foodstuffs industry, the chemical and pharmaceutical industries and similar industries where tanks must be kept clean.
Cleaning is effected by means of liquid supplied under pressure to the apparatus through a pipe, after which it is sprayed out through nozzles which rotate around a horizontal axis as well as around a vertical axis, so that after a certain number of revolutions the apparatus will have cleaned the whole of the inside tank.
Previously known apparatus for this purpose comprised a housing in which there was mounted a turbine in the liquid flow, so that a gear can be coupled to and in extension of the turbine axle. The gear can turn a part of the housing around a vertical axis in relation to the remaining fixed part of the housing, to which is fastened a supply pipe for the liquid.
Mounted radially on the rotatable part of the housing there is a hub on which the nozzles are mounted, in that said nozzles rotate around their horizontal axes by means of a gear exchange. This apparatus is thus driven by the cleaning liquid, in that pressure from the main flow drives the turbine, after which the liquid is led out through an opening in the bottom of the housing. The main flow is deflected in the housing at right-angles and is fed through the hub and out through the nozzles.
However, this construction is encumbered with drawbacks and disadvantages.
First and foremost, there is a considerable loss of energy in the flow of liquid through the apparatus, due particularly to the sharp deflection of the liquid flow.
To this must be added that the apparatus is developed to work only in the vertical position. This limits the use of the apparatus to tanks, where there is access from the top. Finally, there is a risk of the housing becoming sullied both internally and externally by the contents of the tank, and thus the apparatus is unable to function because of the inability to rotate. Similarly, there can be a risk of pollution of the contents of the tank.
In order to overcome these drawbacks, it is known from EP publication no. 0,004,954 to build a turbine into the actual main flow in the apparatus, said turbine being used via a planetary gear to turn both a rotatable part of the housings and a hub with the nozzles, while at the same time the liquid is sprayed out to soften and clean the inside of the tank.
The drive for turning the hub is configured as a conical gear which extends externally on the housing and which is therefore free-lying in the tank. Moreover, the parts are suspended in ball bearings, all of which are contained in totally or partially closed bearing housings.
The result of this construction is that the apparatus has a relatively poor efficiency, especially in strongly polluted environments where the gears easily get sullied, whereby their friction becomes great. In worst case, this can be so high that rotation ceases completely because of the blockage. Furthermore, the mounting of the bearings can give rise to operational problems, in that they are difficult to lubricate and keep clean because of the totally or partially closed mounting. This results in poor lubrication with high friction and consequently, a short lifetime for the bearings.
In addition, the outside of the housing easily becomes dirty, in that the housing cannot avoid being sullied with the tank contents, with the risk that this infiltrates into the housing through drain holes and nozzles. This gives rise to a considerable risk of pollution of the tank contents, and requires a subsequent cleaning both internally as well as externally. Consequently, this means that the apparatus must be cleaned, which is both troublesome and time-consuming.